This invention relates to laser ophthalmic surgery and more particularly to a method and system particularly suited to for photocoagulation procedures performed on a human patient.
Photocoagulation has been used for various ophthalmic procedures with such procedures being performed using either a slit-lamp (SL) laser delivery system or, when surgical intervention is required, endocular laser probes. In the slit-lamp system, laser energy is delivered from the laser source to the imaging optics via a single optical fiber and the procedure can be relatively fast and with good quality results. As is known, the imaging optics is used in conjunction with a variety of contact lenses, and must be capable of focusing the output end (distal) of the fiber onto the retina. The focal length of the imaging optics, is typically variable, i.e. zoom, to magnify the size of the fiber's image on the retina from 1 to 20 times, corresponding to 50-1000 microns on the retina. Current SL systems offer a single fiber for single point exposure on the surgical area. The surgeon positions the fiber image to the desired location by observing a low energy aiming beam on the treatment area. By turning the laser on/off and moving the aiming beam, the surgeon can lay down a pattern of spots on the treatment area. The number of spots is determined by the size of the treatment area and the laser spot size desired. For photocoagulation of micro aneurysms on the retina, the laser spot size should be small (<100 microns) to avoid damage to surrounding tissue.
The time to position the spot and deliver the laser energy depends on the features of the SL and the skill of the surgeon and is typically 1 second per spot. This means that the treatment time is in excess of 30 minutes which is fatiguing to the patient and surgeon. Also, laying down a uniform pattern is difficult and the pattern is typically more random than geometric in distribution. When the treatment requires surgical intervention, the SL is not used and instead a standard endocular laser probes are utilized. The treatment objectives are the same, however, to lay down a pattern of photocoagulative burns in the affected area using the endo-laser (or endocular) probe, the surgeon holds the distal tip close to the retina and lays down 1500-2000 spots, 500 microns in diameter. This procedure can take more than half an hour and using the probe close to the retina may increase the risk of accidental tears with the length of the procedure tending to prolong the anesthesia time in high risk patient groups.
Therefore there is a need for a system that provides the quality and speed of slit lamps systems in an endocular probe oriented procedure.